Container.upload_file assumes a name property on file object

If you try to upload from a file-like object that doesn't have `name`, things blow up:

```
  File ".../pyrax/cf_wrapper/container.py", line 155, in upload_file
    content_encoding=content_encoding, ttl=None)
  File ".../pyrax/cf_wrapper/client.py", line 44, in _wrapped
    return fnc(*args, **kwargs)
  File ".../pyrax/cf_wrapper/client.py", line 603, in upload_file
    fname = file_or_path.name
AttributeError: 'cStringIO.StringO' object has no attribute 'name'
```